With lithium iron phosphate (LiFePO₄ - LFP) batteries exceeding 55% of global EV market share in 2025 and expanding rapidly across emerging markets like Vietnam, managing end-of-life battery waste has become an urgent priority. Among end-of-life battery recycling routes, pyrolysis emerges as the most economically viable option given the low intrinsic value of constituent metals in LFP batteries compared to other chemistries. During reductive co-pyrolysis, in-situ reducing gases derived from biomass can effectively cleave robust metal–oxygen bonds in spent cathode materials, facilitating their conversion into readily leachable phases. In particular, locally abundant corn cobs in Vietnam possess high cellulose contents that generate rich CO and H₂ upon pyrolysis, presenting an ideal feedstock to drive this reductive process. Integrating biomass pyrolysis with spent LFP battery treatment provides a synergistic, sustainable approach to valorize agricultural by-products while facilitating eco-friendly battery recycling. Herein, co-pyrolysis experiments of spent LFP cathodes with corn cobs were conducted across various heating rates and blending ratios. Apparent activation energies were evaluated via Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) isoconversional methods, coupled with FTIR spectroscopy for evolved gas analysis. The results demonstrated that biomass addition significantly altered LFP thermal degradation pathways; in situ generated volatile reductants shifted the decomposition regime toward lower temperatures and markedly reduced activation energy barriers, confirming strong synergistic interactions between the two feedstocks. Overall, this biomass-assisted co-pyrolysis strategy simultaneously valorizes agricultural residues and addresses chemical and economic bottlenecks in battery recycling, offering a sustainable, cost-effective paradigm for industrial-scale spent LFP valorization

Spent LiFePO4 batteries; Biomass co-pyrolysis; Reductive pyrolysis; Battery recycling.